<!DOCTYPE html>
<html lang="cn">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>

</body>

</html>
<script>
    let score;
    score = prompt("请输入你的成绩：");
    if (score >= 90) {
        alert("优秀");
    } else if (score >= 80) {
        alert("良好");
    } else if (score >= 70) {
        alert("中");
    } else if (score >= 60) {
        alert("及格");
    } else {
        alert("不及格");
    }

    // let num1 = 5;

    // num1 += 10;
    // // num1 = num1 + 10;

    // let num2; -->

    // let stra, strb
    // stra = "a";
    // strb = "b";
    // alert(stra < strb);

    // let workTime;
    // // 8 < workTime < 12; 错误
    // 8 < workTime && workTime < 12; //正确
</script>